1. Field of the Invention
The invention relates to concrete building structures and more particularly a building structure and a method of constructing same employing pre-cast modular concrete beams and columns that may be manufactured at the site of the concrete structure. The beams and columns are configured so as to enable the structure to be assembled rapidly, with the modular concrete beams and columns being used to construct the foundation and floor, walls and roof of the concrete structure. In other words, a complete concrete structure is made from one basic member.
2. Description of the Prior Art
Despite the tremendous effort made by the largest companies of the most industralized nations in the world to bring housing construction methods into the twentieth century by industrializing the centuries old methods of hand-making a house by assembling many materials, thousands of pieces, piece by piece with many skilled craftsmen, requiring days or months to build, these efforts have been unsuccessful. This is attested to by the fact that there just are no universally successful systems for housing in the world today, in spite of the critical housing need. Prefabricated and modular housing have been the direction in which most efforts have been made because it was recognized that potentially the best way to construct houses or other structures was with a basic unit or module which would be composed of finished surfaces, be structural and durable, self-insulating and go together to form a structure in a simple manner, such as putting together children's building blocks.
The problem has been that the prefabricated and modular housing industries have simply transferred to a factory these same thousands of pieces, many different materials, many processes and many skilled crafts required, used in the age old construction methods. The cost of the structure completed on the site has not been significantly reduced nor has the modular or prefabricated system significantly reduced the number of skilled crafts required, the many different materials and thousands of pieces required, has not reduced the number of many different steps needed in the construction process, and has only partially reduced the total number of man hours required in the construction process.
That the problem is very complex is attested by the fact that although a great effort has been made to solve the problems, the modular or prefabricated housing industries have only captured an extremely small percentage of the housing market, perhaps as little as 5% after many decades.
The concept of the single building block or module is the correct approach but many complex elements must be a part of the building block, which heretofore have been missing, to make it successful and to solve the problems.
Defining the problem then -- it is to develop a single unit composed of only two or three materials that is structural, insulative and finished on both surfaces, that can be used interchangeably for floors, walls and roofs, that is light enough to be man handled, does not require heavy machinery at the job site, that can be mass produced at the job site but does not require expensive factories, and hence does not occasion great shipping costs, that can build any plan or architectural style and meet any structural requirement, that can be reinforced to resist any dynamic force, that is fireproof, rotproof, vermin-proof, that can be produced from two or three locally available materials and can be put together in a simple manner by unskilled people into an integrated system to form a structure that is virtually complete in one process. This is a big order and heretofore no single unit or single system has combined all of these elements.
First of all a pre-cast concrete unit is the only type of unit that can have any possibility of meeting these many and complex requirements. Even though there have been many, perhaps a thousand of pre-cast units created and many pre-cast concrete systems, not one of these units or systems has met the outlined requirements or combined a combination of even enough of the most important requirements to be universally successful as there just are no universally acceptable pre-cast concrete housing systems. For example, some pre-cast systems are produced in factories, but by the time they are shipped to the job site and put together with heavy machinery the process eliminates any cost savings. Thus, the unit must be able to be mass produced, economically at the job site, and be able to be man handled. Experience has taught that no system, whether pre-cast, cast at the site or whatever, involving heavy equipment and complicated machinery will be successful in housing construction since highly skilled personnel will be required thereby significantly increasing construction costs. Therefore, the requirement that the unit must be able to be man handled is critical.
The pre-cast units with most potential developed heretofore did not provide the necessary means to combine the units into an integrated system that would produce a complete structure and which could be integrally reinforced to meet any of the great variety of critical structural requirements in the building structure itself, nor did they provide for tying all the elements into a monolithic structure with each unit functioning together as a whole.
In summary, the construction industry has continually sought a solution to the problem of building houses of complex design in any architectural style utilizing a basic modular element. The theory has been that if such a basic modular element could be employed, it would greatly reduce the cost of construction, as well as reduce the number of skilled artisans required; reduce the number of and different kinds of material required for construction; reduce the number of different steps in the construction process; and greatly increase the speed of construction in order to satisfy one of mankind's most pressing problems, especially with respect to the construction of low cost housing. Several systems have been developed, all of which relate to the use of concrete which is most capable of providing security against the adverse elements of weather, earthquake, fire and vermin, however, all of such systems have certain significant shortcomings. One such system or technique involves the preliminary erection of a structural steel skeleton arrangement made of I-beams, followed by the placing of large slabs of concrete panels (which are pre-cast at a factory) between the beams. The concrete panels are usually very large, in order to minimize the cost of construction, and hence resort must be made to the use of heavy equipment to transport the panels and to position the panels between the I-beams. Usually this system is only employed with respect to building the up-standing walls of the building structure, whereby resort must be made to conventional building roof techniques to complete the structure. Another disadvantage of this system is that it requires heavy equipment, involves piecemeal construction, and most importantly, requires a huge capital investment in a factory (that necessarily must be remote from the building site) for producing the pre-cast panels. Clearly this technique may not readily be economically employed for the construction of low cost housing in remote locations, where the need for housing is the greatest.
Another known technique for forming concrete buildings is to cast the building in place, by employing a plurality of individual concrete forms that are temporarily secured together to form the wall members, into which the casting concrete is poured. Often these individual forms are made of heavy metal which necessitates the use of construction equipment, with the forms being so constructed that only one design or type of structure can be made. Furthermore, the forms are employed for making the walls of the building, after which conventional roof techniques are employed for completing the structure. Because of the number of pieces of forms that must be assembled, skilled supervisory personnel must constantly be on the job to insure that the forms are properly assembled prior to the casting of the concrete.
Still another technique for forming a concrete structure involves the use of extremely large concrete forms, some large enough to complete major wall portions of a building structure. One obvious disadvantage of this technique is the requirement for heavy equipment for transporting and positioning the forms. After the forms are in position, moist concrete is poured or cast-in-place at the site of the building structure. As in the other techniques, usually a conventional roof structure is then employed for completing the building.
There are many other techniques that are employed for constructing concrete buildings, including a technique where a complete room is constructed at a factory, transported to the job site and several "rooms" are interconnected so as to complete a structure. As noted above with respect to the first mentioned technique, this system requires a huge capital investment for the construction of a factory in order to pre-cast the entire room structure. The costs attendant with the pre-casting of the structure, the transporting to the job site and the problems attendant with the interconnecting of the several rooms usually result in a system where little cost saving is achieved, skilled labor is still required, and little variation in architectural style between adjacent buildings is achieved because of the limitations on variations of the buildings, since they are pre-cast at a central factory.
In light of the shortcomings of the prior art, the system of the present invention is designed to achieve a concrete structure, such as a house, which may be of complex design, in any architectural style, by the interconnection of modular concrete beams, each of which is uniquely constructed so as to be handled by manual labor, readily interconnected, and capable of being combined to result in a complete concrete structure having any desired architectural style or form.